Tamper-evident packaging, and in particular tamper-evident packages for beverages and like products, have met with widespread acceptance in the marketplace. Packages of this nature typically include a bottle or like container molded from polymeric material, and an associated closure, also molded from polymeric material, which cooperates with the container to provide secure and efficient sealing of the package contents. Tamper-evident closures, and associates package constructions, are disclosed in U.S. Pat. No. 4,938,370, No. 5,004,112, No. 5,167,335, No. 5,205,426, and No. 6,557,714, the disclosures of all of which are hereby incorporated by reference.
Notwithstanding the success of molded plastic closures such as configured in accordance with the above-referenced patents, there is currently a heightened awareness in the marketplace with respect to security of beverage packaging. As a result, there is a demand in the market for tamper-evident features, such as typically associated with commercial plastic beverage closure, which are configured such that the tamper-evident feature actuates before the package seal releases. Typical plastic closure beverage technologies available in the marketplace today do not necessarily meet this requirement. As a consequence, under some circumstances it is possible to release a package seal before actuating the associated tamper-evident feature.
Such as disclosed in the above-referenced patents, common tamper-evident technologies associated with plastic beverage closures and containers typically employ a tamper-evident band attached to the closure body via a frangible connection, typically comprising a plurality of circumferentially spaced, frangible bridges. In a typical construction, the tamper-evident band of a closure passes over a continuous locking ring on the container finish during initial application at the bottling line. Upon removal of the closure by the consumer, features on the tamper-evident band, such as disclosed in the above-referenced patents, engage the underside of the container locking ring, and axially retain the band on the bottle. As the consumer continues to rotate the closure to open the package, the frangible bridges are loaded in tension and break, separating the tamper-evident band from the body of the closure, and thus providing irreversible, visually discernible evidence that the package has been previously opened.
Specific characteristics of packaging technology, including plastic closures, have been the subject of careful study and evaluation. One performance aspect relates to the so-called Application Angle, that is, the rotational angle measured from the point at which a closure thread start first engages a bottle thread start during closure application. A target Application Angle, and angular tolerance range, are typically specified by closure manufacturers to ensure proper application of the closure on the bottle at the bottling plant. As can be appreciated, there is inevitably a statistical distribution associated with this angle. This distribution is referred to as the Application Angle Distribution.
Another performance characteristic of tamper-evident packages relates to the unscrewing angle at which the frangible bridges, connecting the tamper-evident band to the closure body, first break. Typically, a range of 50% to 75% bridge breakage is used as a performance standard, and is referred to as the Band Break Angle (BBA). This angle is measured in the unscrewing direction from the fully applied Application Angle. As will be recognized, there is also a statistical distribution associated with this angle. This distribution is called the BBA Distribution.
Another characteristic of this type of package is the unscrewing angle at which the package seal first releases, referred to as the Seal Release Angle (SRA). This angle is measured in the unscrewing direction from the fully applied Application Angle. Again, as will be appreciated, there is a statistical distribution associated with this angle. This distribution is referred to as the SRA Distribution.
The current requirement in the marketplace is that the statistical overlap of the BBA and the SRA distributions will result in a probability that is no greater than 20 to 200 in 10,000 that the BBA will exceed the SRA on any individual package.
Given these performance characteristics of tamper-evident packages, there are two basic approaches to achieving the requirement of breaking the tamper-evident band before the seal releases. The package designer can choose to reduce the average BBA, and associated BBA distribution, and/or, to increase the average SRA and associated SRA distribution. Increasing the average SRA typically results in the addition of extra material in the closure, which undesirably increases cost, and can also be undesirable with respect to opening of carbonated (pressurized) beverage packages. If the SRA is too long, there may not be sufficient time during package opening to release and vent gas pressure from within the package before disengagement of the closure and bottle threads, with the pressure acting against the closure to result in inadvertent displacement of the closure from the container. An efficient manner for achieving tamper-evident band breakage before seal release is to reduce the average BBA angle.
A preferred and viable method for significantly reducing the BBA is to immobilize the tamper-evident band with respect to rotation early in the opening movement of the closure. This can be accomplished by segmenting the locking ring on the closure (thus desirably reducing bottle weight for reduced cost), and providing features on the tamper-evident band that engage the segments on the bottle very early during closure removal. By configuring such bottle segments to include a lead-in angle, or ramped surface, on the application side of the bottle locking ring segments, undesired engagement and trapping of the tamper-band features during application is desirably avoided, avoiding premature fracture of the associated frangible bridges. By designing a blunt edge on the removal side of the locking ring segments, engagement and trapping of the tamper-band features during removal is ensured.
It should be noted that one undesirable aspect of this type of tamper-evident package is that the typical closure frangible bridges, that connect the tamper-evident band to the closure shell, fail and fracture more easily in tension loading than in shear loading. Once the tamper-evident band is prevented from rotating with respect to the closure shell, via engagement of the tamper-evident tabs with the blunt edges of the bottle locking ring segment, the frangible bridges are forced to fail primarily in shear, as a consequence further increasing the torque necessary to break the band, and as a result, the total torque necessary to open the package.
Ideally, the BBA should be as close to zero as possible to achieve a high level of BBA-less-than-SRA performance. However, placing the BBA at or very near zero requires that the consumer must not only overcome the opening torque associated with initially breaking the package seal interface, but must simultaneously overcome the opening torque necessary to break the frangible bridges holding the tamper-evident band to the closure shell. These additive torques results in total package opening torques that are very uncomfortable for the typical consumer, and that are significantly higher than the requirements currently specified by typical beverage producers.
The present invention is directed to embodiments of tamper-evident packages which have been specifically configured to provide enhanced opening performance, by isolating and separating the torque requirements which the package exhibits during initial opening, thereby facilitating convenient use by consumers, while still providing enhanced levels of tamper-evidence.
In accordance with the present invention, performance characteristics have been selected and provided to maximize Opening Torque Margin (OTM), maximize Tamper Evidence Margin (TEM), and maximize Auto-Release Margin (ARM).